save after delete???

1.I got a document (A) by id(XXX)
2.I remove document by id(XXX)
3.I make a change to A
4.I save A

the phenomenon is that:
1. the document is removed eventually.(I am satisfied with this result)
2.after I save a, it won't make a mistake, I got the 'err' to be 'null' (I am not agree with this result)

Start by reproducing the documented sequence: retrieve a document by id, remove it by id, modify the retrieved document, and save it. Check the save callback's err value and confirm the intended behavior for saving after deletion; the issue is done when that behavior is covered by a regression test.

Written by the indexing model from the issue text.